The disclosure of Japanese Patent Application No. 2001-191361 filed on Jun. 25, 2001 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of Invention
The present invention relates to an internal combustion engine having a heat accumulating device and to methods of controlling same.
2. Description of Related Art
Generally, when an internal combustion engine is running under conditions in which the temperature around combustion chambers is below a predetermined temperature, in other words, running under cold conditions there can be difficulty atomizing fuel supplied to the combustion chambers, and quenching around walls of the combustion chambers occurs. Therefore, deterioration in exhaust gas emission and starting performance are induced.
In order to obviate the above-mentioned problems, an internal combustion engine with a heat accumulating device capable of accumulating heat generated by the engine during its running (operation) has been developed. The accumulated heat from the heat accumulating device is supplied to the engine when the engine is at rest or when the engine is started. However, to achieve improvement in emission performance and mileage immediately after the engine is started, it is preferable that the engine reach or exceed a predetermined temperature when it is started, and that it be supplied with the heat before it is started.
The emission performance of the internal combustion engine with the above-described accumulating device depends greatly on whether an insulation function of the heat accumulating device is normal or not. Therefore, a technique for detecting deterioration in the emission performance has been developed.
According to Japanese Patent Laid-Open Publication No. 6-213117, a temperature detecting sensor is provided in a heat accumulator of a heat accumulating device, and a temperature indicating panel in a compartment indicates the detected temperature, so that the temperature in the heat accumulator can be known.
The temperature in the heat accumulator, for example, typically is around 75xc2x0 C. twelve hours after an internal combustion engine is stopped, and around 80xc2x0 C. to 90xc2x0 C. when the engine is running under normal conditions. If the temperature indicated by the temperature indicating panel is around the above-mentioned temperature when the engine is started, this indicates that the temperature of water coolant, which has been accumulated in the heat accumulator, has been kept high. This indicates that the insulation function of the heat accumulating device is normal. If the temperature indicated by the temperature indicating panel is extremely lower than the above-mentioned temperature, on the other hand, this indicates that an abnormality in the insulation function of the heat accumulator in the heat accumulating device may exist.
According to an internal combustion engine with the above-described heat accumulating device, an abnormality in the insulation function is detected based on the assumption that water coolant is accumulated in the heat accumulator in conditions where the engine has sufficiently been warmed up. Therefore, the temperature indicating panel indicates a low temperature if the engine is stopped immediately after the engine is started, i.e., before the water coolant temperature rises sufficiently. It is difficult to distinguish this case from the case where the temperature in the heat accumulator in the heat accumulating device drops because of an abnormality in the insulation function.
In addition, if the coolant is circulated into the engine when the engine is at rest, a low-temperature coolant may flow into the heat accumulating device from the engine. As a result, the temperature indicated by the temperature indicating panel drops. It is also difficult to distinguish this case from the case where the temperature in the heat accumulator in the heat accumulating device drops because of an abnormality in the insulation function.
Furthermore, when an abnormality in a circulation channel for circulating a cooling medium is generated, confirming the abnormality is not possible.
The present invention has been achieved to address the above-mentioned problems, and one object is to allow for the carrying out of a failure determination of a heat accumulating device according to the temperature of a cooling medium in an internal combustion engine having the heat accumulating device.
A first aspect of the invention relates to an engine having a heat accumulating device including a heat accumulator that accumulates heat by storing a heated cooling medium, a heat supplying device for supplying the cooling medium accumulated in the heat accumulator to the engine, and a cooling medium temperature detector that measures the temperature of the cooling medium. The engine further includes a controller that carries out the failure determination of the heat accumulating device according to a variation of values measured by the cooling medium temperature detector when the heat is being supplied by the heat supplying device. According to this aspect of the invention, the failure determination of the heat accumulating device is carried out according to temperature variation in the heat accumulator when the heat is being supplied from the accumulator.
In the internal combustion engine having the heat accumulating device as described above, heat generated during running of the engine can be accumulated by the heat accumulator even after the engine is turned off. The heat accumulated by the heat accumulator can be supplied to the engine through the cooling medium when the engine is started under cold conditions. If the heat is supplied as described above, the engine is warmed up rapidly even when the engine is started under cold conditions.
Meanwhile, if an insulating function of the heat accumulator deteriorates, the temperature of the cooling medium in the heat accumulator drops. As a result, the engine cannot be warmed up by circulating the cooling medium in the engine. Furthermore, if there is an abnormality in the heat accumulator, the engine cannot be warmed up quickly since circulation of the cooling medium is stopped. Under the above-described condition, the temperature measured by the cooling medium temperature detector becomes approximately constant.
Therefore, in the internal combustion engine with the heat accumulating device according to this aspect of the invention, the failure of the heat accumulating device can be determined according to the value measured by the cooling medium temperature detector when the heat is supplied from the accumulator.
A second aspect of the invention related to an engine having a heat accumulating device including a heat accumulator for accumulating heat by storing a heated cooling medium, a heat supplying device for supplying the cooling medium accumulated in the heat accumulator to the engine, an in-heat accumulator detector that measures the temperature of the cooling medium in the heat accumulator, and an in-engine temperature detector that measures the temperature of the cooling medium in the engine. The engine further includes a controller that carries out the failure determination of the heat accumulating device according to whether there is a difference between a value measured by the in-heat accumulator temperature detector and the value measured by the in-engine temperature detector when the heat is being supplied by the heat supplying device or before the heat is supplied therefrom. According to this aspect of the invention, the failure determination of the heat accumulating device is carried out according to whether there is a difference between the value measured by the in-heat accumulator temperature detector and the value measured by the in-engine temperature detector.
In the internal combustion engine having the heat accumulating device as described above, heat generated during running of the engine can be accumulated by the heat accumulator even after the engine is turned off. The heat accumulated by the heat accumulator can be supplied to the engine through the cooling medium when the engine is started under cold conditions. If the heat is supplied as described above, the engine is warmed up rapidly even when the engine is started under cold conditions. When the heat supply is completed, the temperatures of the cooling medium in the heat accumulator and the engine become approximately the same.
Meanwhile, if there is an abnormality in the heat supplying device, the engine is not warmed up, and the heat accumulator keeps storing the heat. At this time, the difference between the temperature in the heat accumulator and that in the engine does not change or it changes a little, if any.
Therefore, in the internal combustion engine having the heat accumulating device according to this aspect of the invention, the failure of the heat accumulating device can be determined according to the difference between the temperature in the heat accumulator and that in the engine when the heat is supplied from the accumulator.
A third aspect of the invention relates to a heat accumulating device including a heat accumulator that accumulates heat by storing a heated cooling medium, a heat supplying device that supplies the cooling medium accumulated in the heat accumulator to the engine, an in-heat accumulator temperature detector that measures the temperature of the cooling medium in the heat accumulator, and an in-engine temperature detector that measures the temperature of the cooling medium in the engine. The engine further includes a controller that carries out the failure determination of the heat accumulating device according to a difference between a value measured by the in-heat accumulator temperature detector and one by the in-engine temperature detector when a predetermined time elapses after the engine is turned off. According to this aspect of the invention, the failure determination of the heat accumulating device is carried out according to whether there is a difference between the value measured by the in-heat accumulator temperature detector and that by the in-engine temperature detector when the predetermined time elapses after the engine is turned off.
A fourth aspect of the invention relates to an engine having a heat accumulating device including a heat accumulator that accumulates heat by storing a heated cooling medium, a heat supplying device that supplies the cooling medium accumulated in the heat accumulator to the engine, and a cooling medium heater that automatically heats the cooling medium in the heat accumulator to keep the temperature of the cooling medium equal to or higher than a predetermined temperature. The engine further includes a controller that carries out the failure determination of the heat accumulating device according to a driving history of the cooling medium heater when a predetermined time elapses after the engine is turned off. According to this aspect of the invention, the failure determination of the heat accumulating device is carried out according to the driving history of the cooling medium heater when the predetermined time elapses after the engine is turned off.
In the internal combustion engine having the heat accumulating device as described above, heat generated during running of the engine can be accumulated by the heat accumulator even after the engine is turned off. The heat accumulated by the heat accumulator can be supplied to the engine through the cooling medium when the engine is started under cold conditions. If the heat is supplied as described above, the engine is warmed up rapidly even when the engine is started under cold conditions. When the heat supply is completed, the temperatures of the cooling medium in the heat accumulator and the engine become approximately the same.
Meanwhile, a small amount of heat is emitted out of the heat accumulator, so that the temperature in the heat accumulator drops. To compensate for the emitted heat, the cooling medium heater is provided to heat the cooling medium. If the insulation performance of the heat accumulator is not deteriorating, the amount of heat emitted out of the heat accumulator is small, so that the amount of heat applied to the cooling medium by the cooling medium heater is also small. However, if the insulation performance of the heat accumulator deteriorates, the amount of heat emitted out of the heat accumulator becomes larger, so that the amount of heat applied to the cooling medium by the cooling medium heater also becomes larger.
Therefore, in the internal combustion engine having the heat accumulating device according to this aspect of the invention, the controller can determine a failure of the heat accumulating device according to the driving history of the cooling medium heater.
A fifth aspect of the invention relates to an engine having a heat accumulating device including a heat accumulator that accumulates heat by storing a heated cooling medium, a heat supplying device that supplies the cooling medium accumulated in the heat accumulator to the engine, a cooling medium heater that automatically heats the cooling medium in the heat accumulator to keep the temperature of the cooling medium equal to or higher than a predetermined temperature, and an in-heat accumulator temperature detector that measures the temperature of the cooling medium in the heat accumulator. The engine further includes a controller that carries out the failure determination of the heat accumulating device according to a measuring result by the in-heat accumulator temperature detector when a predetermined time elapses after the engine is turned off. According to this aspect of the invention, the failure determination of the heat accumulating device is carried out according to a measuring result by the in-heat accumulator temperature detector when the predetermined time elapses after the engine is turned off.
In the internal combustion engine having the heat accumulating device as described above, heat generated during running of the engine can be accumulated by the heat accumulator even after the engine is turned off. The heat accumulated by the heat accumulator can be supplied to the engine through the cooling medium when the engine is started under cold conditions. If the heat is supplied as described above, the engine is warmed up rapidly even when the engine is started under cold conditions. When the heat supply is completed, the temperatures of the cooling medium in the heat accumulator and the engine become approximately the same.
Meanwhile, as described above, a small amount of heat is emitted out of the heat accumulator, so that the temperature in the heat accumulator drops. To compensate for the emitted heat, the cooling medium heater is provided to heat the cooling medium. If the insulation performance of the heat accumulator is not deteriorating, the amount of heat emitted out of the heat accumulator is small, so that the amount of heat applied to the cooling medium by the cooling medium heater is also small. However, if the insulation performance of the heat accumulator deteriorates, the amount of heat emitted out of the heat accumulator becomes larger, so that the amount of heat applied to the cooling medium by the cooling medium heater also becomes larger. At this time, if the amount of the heat emitted out of the heat accumulator is larger than the amount of heat supplied by the cooling medium heater, the temperature of the cooling medium in the heat accumulator drops. Furthermore, the temperature of the cooling medium in the heat accumulator also drops if there is a failure of the cooling medium heater.
Therefore, in the internal combustion engine having the heat accumulating device according to this aspect of the invention, the controller can determine a failure of the heat accumulating device according to a measuring result by the in-heat accumulator temperature detector when the predetermined time elapses after the engine is turned off.